Heavily armed police and soldiers moved into Rio de Janeiro's largest slum early yesterday in an operation that officials claimed as a significant victory in the battle to rid the city of its ruthless drug gangs.

Helicopters hovered as hundreds of police, supported by the Brazilian army, flooded into Rocinha, a labyrinth of ramshackle houses perched on a hill overlooking some of Rio's most affluent neighbourhoods. The slum is thought to be the source of much of the cocaine distributed in the city. Not a single shot was fired and, according to reports, just one person was arrested, in an apparent vindication of the authorities' decision to announce the raid days earlier to avoid bloody gun battles.

Rocinha is the latest of several slums to be occupied as the city cracks down on violent crime ahead of the 2014 World Cup, which Brazil will host, and the 2016 Olympic Games, to be held in Rio.

Home to some 100,000 of Rio's poorest residents, Rocinha is regarded as particularly strategic as its hilltop location potentially controls traffic from central Rio to the west of the city, where most of the Olympic events will be staged. Wilson Aracanju, an evangelical pastor who watched the police operation from his church, said: "I am hopeful, but they have to do much more. The community needs healthcare, education and other social services." The raid was the second major blow against Rio's drug gangs in the past week after the arrest on Thursday of Antonio Francisco Bonfim Lopes, the gang boss said to run Rocinha. Caught by police while hiding in a car boot, Lopes is thought to have overseen a network of drug dealers earning more than £30m a year.

The tactic of announcing the raid was developed after 36 people died last November when Rio's drugs gangs went on a bloody week-long rampage.

The police then occupied Alemao, a huge slum on Rio's north side with a terrifying reputation. Although that operation was a success, officers believed they should control the timing of future operations rather than responding to the gangs' actions.